[Paul] says to the Thessalonians: you must not “grieve as others do who have no hope” (Th 4:13). Here too we see as a distinguishing mark of Christians the fact that they have a future: it is not that they know the details of what awaits them, but they know in general terms that their life will not end in emptiness. Only when the future is certain as a positive reality does it become possible to live the present as well. So now we can say: Christianity was not only “good news”–the communication of a hitherto unknown content. In our language we would say: the Christian message was not only “informative” but “performative”. That means: the Gospel is not merely a communication of things that can be known–it is one that makes things happen and is life-changing. The dark door of time, of the future, has been thrown open. The one who has hope lives differently; the one who hopes has been granted the gift of a new life.

– pp. 9-10

This is only about 100 pages. The final one-third of the encyclical, which provides a great illumination on the topic of Purgatory, is particularly strong.